This invention relates generally to automatic dough producing systems, and more particularly to a system whose respective stages, such as those required for mixing flour and a dough-forming solution and for kneading and developing the dough, are separately controllable, making it possible to optimize the conditions prevailing in each stage.
From the standpoint of production volume, bread is the most important baked product. Mixing is the first active step in bread production. The ingredients involved in mixing are flour and a dough-forming solution constituted typically by water, yeast, sugar, salt, milk and shortening. Ideally, mixing should result in a uniform mixture forming a smooth dough; it should develop the gluten in the dough in order to promote the elasticity of the dough and permit it to retain the gases generated by the yeast; and it should distribute the yeast cells uniformly so that they will receive proper nutrition.
In traditional techniques for producing dough, such as the batch method in which heavy blades revolve in a large bowl act to mix the flour and dough-forming solution into a homogeneous mass, a number of steps must be separately performed which render the process time-consuming and costly. Moreover, the resultant dough is not entirely homogeneous, giving rise to non-uniform dough balls and a final baked product of unpredictable consistency.
The fact that dough can be rapidly produced has been confirmed by Bernadin et al. in their article "Hydrated Protein Fibrils from Wheat Endosperm" in the periodical Cereal Chemistry--September-October 1968, Vol. 50, No. 5. This article points out that flour hydration occurs very rapidly; for wetting a single particle of four in a droplet of water requires less than 0.05 sec. for complete hydration, a hydrated protein web spreading quickly from the particle. Adjacent flour particles spreading similar protein networks interact to form a continuous system that can be worked mechanically to form a dough-like mass.
In my prior patent, a screw rotating within a vertical tubular chamber acts to centrifugally hurl flour fed into the chamber against the inner wall thereof, thereby depositing a thin film of flour on the inner wall. Also fed into the chamber is the dough-forming solution which is projected centrifugally against the thin film of flour to form on the inner wall a pasty film that is directed downwardly along a helical path. The pasty film is scraped from the inner wall to produce a downwardly-extending ribbon that is then subjected to a kneading and developing action.
The flour fed into the mixing chamber is introduced therein through a hopper having an outlet of fixed dimensions. The practical difficulty with this fixed feed arrangement is that it fails to take into account the changing flowability of flour with variations in ambient temperature and humidity. Also, it does not accommodate the feed to the disparate characteristics of various flours. One, therefore, is not always able to attain optimum flour flow conditions.
Flour, which is a finely ground meal of wheat, is the backbone and structure of baked good, flour acting both as a binding and absorbing agent. Wheat is the only cereal that contains the proper combination of glutenin and gliadin for bread-making. When combined with water, these constituents form gluten which is essential for retaining the gas produced by yeast. The form of wheat used depends on the ultimate product. Thus there are several kinds of so-called hard wheat, the choice depending on the final product (i.e., rolls or bread). Cakes and cookies are derived from various types of soft wheat. In some instances, rye flour milled from rye grain may be blended into wheat flour.
In my above-identified copending application of which the present application is a continuation-in-part, means are provided in an apparatus generally of the type disclosed in my prior patent, to adjust the input feed of flour thereto to accommodate the machine to changing ambient conditions and to different flour characteristics. The arrangement is such as to effect continuous mixing of flour and a dough-forming solution, the solution being produced continuously at a rate in accordance with the demand therefor.
In the apparatus disclosed in my copending application, rotating within a lined cylindrical chamber is a screw, the chamber having a film-forming zone therein in which incoming flour particles are hurled by the screw against the surface of the liner to form thereon a thin, downwardly moving flour film. In the succeeding atomizing zone, the film or flour is admixed with the dough-forming solution to produce a pasty mass in film form. In the next zone, this pasty mass is then subjected to a kneading action to effect development, the developed mass then entering proofing and dough-dividing stages.
In the apparatus disclosed in my copending application, the development zone is integrated with the preceding atomizing and mixing zones, for the screw is common thereto. Hence if one adjusts the speed of screw rotation to optimize the activity being carried out in the paste-forming zone, this adjustment may at the same time adversely affect the development action in the succeeding zone. Thus for a given adjustment, the degree of development may be inadequate, causing the dough to lack homogeneous qualities; or it may be excessive, causing the dough to take on undesirable rubber-like characteristics.